This invention relates to a laser beam generating unit for collecting laser beam emitted from a plurality of beam emitting portions (emitters) of a semiconductor laser in order to utilize for desired usage.
Generally, a semiconductor laser (laser diode: LD) is known as a source of laser beam having high conversion efficiency from electricity into light, and the efficiency of laser beam exceeding 50 percent, and then, a big scale of cooling unit is not necessary. Therefore, the semiconductor laser is utilized in the field of information processing industry since it can be made compact. But, this semiconductor laser has not been used in the field of machining with laser beam since the size of laser beam of this semiconductor laser is 1 mm or lower at the most and only several watt (W) of beam output is expected although the semiconductor laser has high efficiency of laser beam.
In recent years, a semiconductor laser beam collecting machine to be used for machining with laser beam by using a plurality of semiconductor lasers which are one-dimensionally or two-dimensionally arranged has been planned (see FIGS. 1 through 3 of the Japanese patent application (Publication No.H07-168040). This semiconductor laser collecting machine can obtain high output of laser beam having high light density since a plurality of semiconductor lasers are used although output of laser beam from one semiconductor laser is small.
This semiconductor laser beam collecting machine disclosed in this patent application collects laser beam emitted from the respective beam emitting portions which are sources of laser beam of a semiconductor laser substrate through a beam guiding path formed at the substrate so as to raise the output in order to utilize machining with laser beam. The beam guiding path has input ports having the same number as the sources of laser beam at one end, and all of the laser beam received at each input port is transmitted for only one output port which is formed at the other end.
According to the above-mentioned semiconductor laser beam collecting machine, a relatively big basic plate having a beam guiding path is necessary to be separately prepared in order to collect laser beam emitted from a plurality of beam emitting portions. Dew to the presence of such a basic plate, the machine is not made compact.
Then, an attention is paid to such a structure that laser beam is collected from each of beam emitting ends of the optical fiber bundle which is made by binding a plurality of optical fibers without using the above-mentioned substrate. In such a case, the diameter of the bound portion of the optical fiber bundle is big. In order to collect lower output of laser beam from many beam emitting portions and obtain high output of laser beam, the number of the optical fibers increases, and invites power density down. For this reason, it is desired to make the diameter of the optical fiber bundle smaller on the beam emitting side if the optical fibers are used as the laser beam collecting means.
Then, laser beam generating units for collecting laser beam emitted from each of beam emitting portions with high efficiency by a combination of laser beam collecting means and a taper beam transmitting path are still desired.